1. Field of the Invention
This invention relates to a shock absorbing bow stabilizer that is mounted to an archery bow, for one reason to reduce recoil, shock, vibration and noise when an arrow is shot from the archery bow. More specifically, this invention relates to a shock absorbing bow stabilizer having at least one element, for example an energy director, at least a portion of which is disposed within a chamber of the bow stabilizer to deflect the movement of fill particles in a radially outward direction to decrease the vibration amplitude during a recoil cycle.
2. Description of Related Art
Various bow stabilizers and vibration dampeners have been developed to absorb shock when an arrow is shot from an archery bow. These conventional bow stabilizers generally have a hollow cylinder filled either with a viscous fluid or solid particles to attenuate vibration when an archery arrow is released from an archery bow. For example, one conventional bow stabilizer has a hollow body that defines a sealed chamber that is partially filled with granular solids. The bow stabilizer is mounted to the archery bow and has a counterweight that is fixedly adjustable along a longitudinal axis of the elongated hollow body. The hollow body has two end plugs, each end plug having a connecting portion connected to a plug portion. The connecting portion has a peripheral knurled surface to secure the end plug to the hollow body of the bow stabilizer. The end plugs are typically press fitted to the hollow body to contain the granular solids within the hollow body.
After the archery arrow is released from the archery bow, the archery bow recoils in a cyclic fashion. During a first recoil, the granular solid particles move in a direction towards a first end portion of the chamber and collide with an interior surface of the end plug which seals the opening at the first end portion. During an opposite second recoil, the granular solid particles move in a direction toward a second end portion of the chamber and collide with an interior surface of the end plug which seals the opening at the proximal end portion. This cycle of recoils continues for several milliseconds before the archery bow comes to rest. Because the interior surfaces of the end plugs can be generally flat, a relatively large number of particles collide with the interior surfaces during the recoil cycle. The impact of the particles with the interior surfaces of the bow stabilizer contributes to a recoil vibration having an increased amplitude.
Accordingly, there is an apparent need for a bow stabilizer which experiences a decreased vibration amplitude during the recoil cycle after an archery arrow has been released from the archery bow.
It is also apparent that there is a need for an element, for example an energy director, positionable within a chamber of the bow stabilizer to direct particles in a generally outward radial direction, thereby decreasing the number of particles which collide with the interior surfaces of the end plugs during the recoil cycle.
It is an object of this invention to provide an insert for deforming a resilient plug and thereby enlarging an outer surface of the removably mounted resilient plug, to sealably close an opening in a hollow body of the bow stabilizer.
It is another object of this invention to provide a bow stabilizer having a decreased vibration amplitude during a recoil cycle after an archery arrow is released from the archery bow.
It is another object of this invention to provide at least one element, for example an energy director, at least partially exposed within a chamber, having an outer surface which deflects the movement of fill particles in a generally outward radial direction towards an internal surface of a hollow body forming the chamber.
The above and other objects of this invention are accomplished with a bow stabilizer for an archery bow having a hollow body, preferably constructed of a suitable, lightweight, rigid material which resists corrosion and deterioration.
At least a portion of the hollow body forms a chamber at least partially filled with a solid and/or a liquid. In one preferred embodiment of this invention, a first plug is removably mounted within an opening at a proximal end portion of the hollow body and a second plug is removably mounted within an opening at a distal end portion of the hollow body to close each opening and sealably contain the fill within the chamber. Preferably, but not necessarily, the second plug is the same as or similar to the first plug. In one preferred embodiment, each plug is made of a resiliently deformable material that is deformed when a compression force is applied to at least a portion of the plug but preferably returns to its initial shape when the compression force is removed.
The first plug and the second plug each forms a bore which is coaxially aligned with a longitudinal chamber axis. At least a portion of each plug has an outer surface having a peripheral shape that corresponds to the shape of the internal surface of the hollow body, thereby forming a tight seal between the plug and the hollow body.
In one preferred embodiment of this invention, an insert is positionable within the bore formed by each of the first plug and the second plug, using conventional means, for example press-fitting the insert within the bore. Preferably, the insert is made of a metal or metal alloy, such as steel or brass. The insert has a shaft which extends through the bore when the insert is positioned within the plug. Preferably, the shaft has a plurality of ribs or projections which extend radially from a periphery of the shaft. The projections ensure that the insert is securely positioned within the bore and that the inner portion of each plug is enlarged so that the outer surface contacts the internal surface of the hollow body to tightly seal and contain the fill within the chamber.
The shaft which is positionable within the first plug preferably forms a second bore having a plurality of internal threads about an interior surface of the shaft forming the second bore for threaded engagement with a first end portion of a mounting stud. A second end portion of the mounting stud is threadedly engageable with a threaded female coupling of the archery bow to secure the bow stabilizer to the archery bow.
The insert which is positionable within the second plug preferably has a flange about a periphery of the insert to radially interfere with at least a portion of an exterior surface of the second plug. The first plug and the second plug are easily removable from the corresponding opening by removing the respective insert.
In one preferred embodiment of this invention, an element, for example an energy director, extends from the first plug and at least a portion of the element is exposed within the chamber. The element has a longitudinal element axis which is preferably coaxially aligned with the longitudinal chamber axis and is made of a resiliently deformable material, for example a natural or synthetic rubber, another polymeric material or a composite material. The element has a fixed end portion contacting or abutting an inner wall or surface of the first plug and a free end portion at a distance from the first plug. The fixed end portion has a distal wall or surface which radially interferes with at least a portion of the inner surface of the first plug. The element is attached or connected to the shaft of the insert positioned within the first plug.
At least a portion of the element preferably converges in a direction from the fixed end portion to the free end portion, along the longitudinal chamber axis. Preferably but not necessarily, the element has an outer surface having a generally conical shape.
Similarly, a second element extends from the second plug and at least a portion of the second element is exposed within the chamber. The second element has a longitudinal element axis which is aligned with the longitudinal chamber axis. Preferably, the second element is made of a resiliently deformable material, the same or similar to the material used to make the first element. The second element has a fixed end portion contacting or abutting an inner wall or surface of the second plug and a free end portion at a distance from the second plug. The fixed end portion has a distal wall or surface which radially interferes with at least a portion of the inner surface of the second plug. The second element may be attached or connected to the shaft of the insert positioned within the second plug.
At least a portion of the second element preferably converges in a direction from the fixed end portion to the free end portion, along the longitudinal chamber axis. Preferably but not necessarily, the second element has an outer surface having a general conical shape suitable for altering or deflecting the direction of particle movement within the chamber.
In accordance with this invention, the bow stabilizer having at least one element at least partially exposed within the chamber, decreases the amplitude of the recoil vibration after release of an archery arrow. During a recoil cycle, the fill particles impact the element and the direction of the relative movement of at least a portion of the fill particles is altered or deflected in a generally radial direction, i.e. towards the internal surface of the hollow body. As a result of this deflection in direction of movement, more particle-particle collisions occur. These particle-particle or intraparticle collisions disrupt the movement of the fill generally toward the inner surface of the first plug and/or the inner surface of the second plug. As a result, the vibration amplitude during the recoil cycle is decreased.